1. Field of Invention
The invention relates to visual displays. More particularly, the invention relates to nonspecular, reusable, paper-like, gyricon or twisting-particle type or other visual displays and method.
2. Description of Related Art
Paper is a preferred medium to present and display text and images. A reason for paper being a preferred medium is the many advantages that are realized with the use of paper as a display medium. For example, paper is thin, lightweight, portable, flexible, foldable, cost efficient, high contrast, reusable, basically permanent, and can easily be configured into a multitude of shapes. In addition, paper does not have any limitations on size, other than practicality, and as such, can be used as display media such as, for example, sticky notes or such, maps and billboards, to name a few. Furthermore, paper is capable of maintaining a displayed image without the need for a power source, such as, for example, batteries and other such stored energy sources. In addition, paper can be read in ambient light, as well as marked upon with any number of implements, such as, for example, a pen, pencil, paintbrush, printers, photocopiers, and the like.
Additionally, one feature of using paper as a display medium is paper does not suffer from specular reflection. In other words, there is no mirror-like or direct reflection of light from a light source off the viewed surface of paper like that found in conventional cathode-ray tube (CRT) displays. Specularly reflected light on a television or computer screen, for example, produces an annoying glare such that a viewer must reposition his head to not look at the direct reflection of light. In contrast, because the viewed surface of paper is usually rough, for example, light is scattered diffusely by the viewed surface so that the viewer can look directly at the paper in a comfortable manner.
However, although paper has many advantages as a display medium, paper is not well suited for real-time display purposes. Real-time imagery from computer, video, and other sources cannot be displayed by means other than, for example, a CRT display or a liquid-crystal display (LCD). Unfortunately, most real-time display media lack many of the desirable advantages of paper, such as, for example, being lightweight, thin, portable, physically flexible, and the ability to retain a displayed image in a stable manner without a power source. Furthermore, because most real-time display media use a flat glass display surface, such media specularly reflect light and produce an annoying glare. As such, attempts have been made to combine the desirable qualities of paper with those of real-time display media in order to provide a display that offers the best of both worlds. One such display is electric paper.
Like paper, electric paper can be written on and erased, can be read in ambient light, and can retain information in the absence of an electric field or other external retaining force. Also, like ordinary paper, electric paper can be made in the form of a lightweight, flexible, durable sheet that can be folded or rolled into tubular form about any axis and conveniently placed into a shirt or coat pocket, and then later retrieved, restraightened, and read substantially without loss of information. Yet, unlike paper, electric paper possibly can be used to display imagery in motion. Thus, electric paper is adaptable for use in computer systems, television, signs and a host of other applications within office, industrial and domestic settings.
One such form of electric paper is a gyricon display, also called a twisting-element display, rotary element display, particle display, dipolar particle light valve, and the like. Briefly, a gyricon display includes a plurality of optically anisotropic particles, such as, for example, spheres, each of which can be selectively rotated to present a desired image to an observer. For example, a gyricon display can incorporate rotational elements each having two distinct halves, e.g., one half may be black, while the other half is white.
The rotational elements are embedded in a sheet of optically transparent material that contains a plurality of cavities and is permeated by an optically transparent dielectric fluid. The fluid-filled cavities accommodate the rotational elements, one element per cavity, so as to prevent the elements from migrating within the sheet. Each element has a distinct electrical characteristic so that the elements are electrically as well as optically anisotropic. Thus, an element can be selectively rotated within its respective cavity by application of an electric field, so as to present either the black or the white half to an observer viewing the surface of the sheet, for example. However, as with most real-time display media, electric paper displays also typically have a substantially transparent flat surface that subjects a viewer to the annoying glare associated with the specular reflected which prevents the viewer from seeing the diffuse light scattered off the surface of the rotational elements.
Many attempts have been made to solve the problem of specular reflection. An example of such a solution is the roughening of the viewed surface of the display media, as seen in such displays as, for example, automatic teller machines, hand-held calculators and laptop computers. However, the added scattering in the dark regions of the display and the distortion of the image viewed through the rough surface are considered to significantly degrade the performance of the display. Additionally, certain real-time display media, such as a CRT, cannot roughen the viewed surface because the integrity of the flat surface is weakened, thereby subjecting the CRT to breakage.
The invention provides a nonspecular visual display and method in which the display achieves an appearance much like paper.
In one aspect, the invention uses a substantially thin encapsulation layer that conforms to the shape of elements in the display. The conformal layer of encapsulation material of the display achieves a paper-like appearance because there is no specular reflection of light produced by the conformal layer. In other words, light is diffusely reflected by the surface of the conformal layer.
In another aspect of the invention, microencapulated display elements are formed on a substrate. Since there is no top layer covering the display elements, ambient light is not specularly reflected by the display.
These and other aspects of the invention will be described in or be apparent from the following description of specific embodiments.